[USRP-users] Question related to captured data validation

Marcus D. Leech mleech at ripnet.com
Wed Oct 14 11:17:06 EDT 2015


On 10/14/2015 12:16 AM, alok ranjan via USRP-users wrote:
> Hello All,
>
> I am using two USRP N210, one as a transmitter and another one as a 
> receiver both are connected to the same host.
>
> However, both  USRPs are separated from each other (say 2, 4, 6, 8, 10 
> meters).
>
> For my initial studies I am using *benchmark_tx * programme for 
> transmitting the signals and *benchmark_rx* for the reception purpose.
>
> Next, I am capturing the transmitted base band signals (Complex) using 
> the *uhd_rx_cfile* with all the valid assignments to be passed. I am 
> giving  all the valid configuration same as the configuration 
> maintained while reception.
>
> *In the next step, i am converting the complex data captured (using 
> the uhd_rx_cfile) into .mat format with the help of "Octave".*
>
>
> I would like to know that how to validate that the data i have 
> captured using uhd_rx_cfile is valid and having the information of 
> transmitted signals.
It depends on what you mean by "valid".  The data in the file are 
complex samples proportional to the instantaneous voltages seen
   at the antenna port.  SIgnal processing/DSP/SDR is about extracting 
the information that has been impressed-upon (modulated)
   onto those samples.  That's what benchmark_rx does.

Your question is a very-general DSP question, and not really 
specifically related to USRPs, and the examples you cite are part of
   Gnu Radio, not UHD.   You'd do better to ask general DSP questions on 
the discuss-gnuradio list.


>
>  Also, is it a good practice to use the converted .mat data to extract 
> the Average RSSI per samples using the convolution formula i.e.
>
> *Conv(abs(IQ data vector).^2, ones(1,N)/N,'valid').*
> *
> *

The instantaneous power of a complex signal is  I^2 + Q^2.  You can then 
average as you see fit.

Again, this is a general DSP question, and the discuss-gnuradio mailing 
list would be a better forum.

b
> *
> *
> Any help in this matter is appreciated.
>
> Thank you, regards
>
> Alok Ranjan
>
>
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